The driver, which was developed for several months by a LunarG employee as "i965g" for Gen6/Gen7 hardware, in the process of being merged was renamed to "ilo" to avoid confusion with the official Intel i965 DRI driver. Intel does not support the i915g or ilo Gallium3D graphics drivers.
Earlier this month I delivered Intel Gallium3D driver benchmarks showing the state of this alternative open-source Intel Linux graphics driver from HD 4000 graphics.
The driver was merged to master earlier today with a series of ilo commits. The driver isn't enabled by default but requires passing the --with-gallium-drivers=ilo argument.
The driver right now is also continuing to use the "toy" compiler rather than sharing the Intel i965 shader compiler back-end or having a proper optimizing compiler.